Common timestamp attributes in Linux file systems

Common time attributes in Linux file systems include access time (atime), modification time (mtime) and change time (ctime). These time attributes record different operation times of files or directories, and are very important for file system management and tracking. The following will introduce these three time attributes one by one, with corresponding code examples.

1. Access time (atime)

Access time refers to the last time a file or directory was accessed or executed. When the file is read, executed or viewed, the access time is updated. In most cases, atime will be automatically updated by the system, but it can also be disabled through settings. The following is a simple example:

touch example.txt
ls -l example.txt
# 输出示例：-rw-rw-r-- 1 user user 0 Dec 1 00:00 example.txt
cat example.txt
ls -l example.txt
# 输出示例：-rw-rw-r-- 1 user user 0 Dec 1 01:00 example.txt

In the above example, we created a file named example.txt and viewed the contents of the file through the cat command so that the access time was updated.

2. Modification time (mtime)

Modification time refers to the time when the file content was last modified. When the file content is modified, the modification time is updated. The following is an example of modification time:

touch example.txt
ls -l example.txt
# 输出示例：-rw-rw-r-- 1 user user 0 Dec 1 00:00 example.txt
echo "Hello World" > example.txt
ls -l example.txt
# 输出示例：-rw-rw-r-- 1 user user 12 Dec 1 01:00 example.txt

In the above example, we wrote content to example.txt through the echo command, so that the modification time is updated.

3. Change time (ctime)

Change time refers to the time when the i-node (inode) information of the file was last modified. When a file's permissions, owner, or other metadata change, the change time is updated. The following is an example of changing the time:

touch example.txt
ls -l example.txt
# 输出示例：-rw-rw-r-- 1 user user 0 Dec 1 00:00 example.txt
chmod 777 example.txt
ls -l example.txt
# 输出示例：-rwxrwxrwx 1 user user 0 Dec 1 01:00 example.txt

In the above example, we modified the permissions of the example.txt file through the chmod command, so that the change time is updated.

Summary: The time attributes in the Linux file system include access time, modification time and change time, which each record the time information of different operations on the file or directory. Through the demonstration of code examples, you can more intuitively understand how these time attributes are applied and updated in the Linux system.

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